drop Groovy 6 workarounds whose upstream fixes have merged

Re-audited every Groovy 6 workaround in this canary against the latest
Apache Groovy master. Three fixes have merged and are present in the
6.0.0-SNAPSHOT artifact (latest publication: 2026-05-02 11:47:43 UTC,
build #546), so the corresponding workarounds can be removed.

GROOVY-11968 (apache/groovy#2495), merged 2026-05-01 03:40 UTC,
SHA 84f2f37c4f93d6ea44ad8bc76570704c84499c6b
  - grails-geb/.../ContainerSupport.groovy: revert @CompileDynamic to
    @CompileStatic now that the trait-static-field VerifyError under
    indy=false no longer triggers.

GROOVY-11967 (apache/groovy#2493), merged 2026-05-01 09:37 UTC,
SHA 406feaf5082f1741c318f924b520c4c27bfa0754
  - DefaultConstraintFactory.groovy: collapse the two explicit
    constructors back to a single constructor with a default-valued
    List parameter; the @CompileStatic VerifyError on the synthesised
    bridge constructor no longer reproduces.
  - MappingContextAwareConstraintFactory.groovy: same collapse.

GROOVY-11966 (apache/groovy#2492), merged 2026-05-01 18:58 UTC,
SHA 8dde1c84134ef6fdeecf26b5cbb5183d5aab4dac
  - GroovyPageCompiler.groovy: drop the parallelism guard and the
    grails.gsp.compiler.parallelism system property; restore the
    original Executors.newFixedThreadPool(availableProcessors() * 2)
    sizing now that AnnotationNode.isTargetAllowed -> ListHashMap is
    thread-safe again.
  - AbstractGroovyTemplateCompiler.groovy: same restoration; drop the
    grails.views.compiler.parallelism system property.

Verified locally on Java 21 / Groovy 6.0.0-SNAPSHOT build #546:
  ./gradlew :grails-datamapping-validation:compileGroovy
  ./gradlew :grails-datamapping-core:compileGroovy
  ./gradlew :grails-gsp-core:compileGroovy
  ./gradlew :grails-views-core:compileGroovy
  ./gradlew :grails-geb:compileTestFixturesGroovy
  -> all BUILD SUCCESSFUL

The remaining workarounds (TraitReceiverTransformer static-method
override loss, MetaClassImpl genericGetMethod hijack on GORM entities,
@CompileStatic named-argument render(Map) silent no-op, smart-cast
in 'if (cond && !(x instanceof Y))', VariableScopeVisitor NPE, and
ConfigObject [] mutation) have no upstream fix yet and stay in place.

Author: James Fredley

grails-datamapping-core/src/main/groovy/org/grails/datastore/gorm/validation/constraints/MappingContextAwareConstraintFactory.groovy

@@ -35,11 +35,7 @@ class MappingContextAwareConstraintFactory extends DefaultConstraintFactory {
 
     final MappingContext mappingContext
 
-    MappingContextAwareConstraintFactory(Class<? extends Constraint> constraintClass, MessageSource messageSource, MappingContext mappingContext) {
-        this(constraintClass, messageSource, mappingContext, [Object] as List<Class>)
-    }
-
-    MappingContextAwareConstraintFactory(Class<? extends Constraint> constraintClass, MessageSource messageSource, MappingContext mappingContext, List<Class> targetTypes) {
+    MappingContextAwareConstraintFactory(Class<? extends Constraint> constraintClass, MessageSource messageSource, MappingContext mappingContext, List<Class> targetTypes = [Object]) {
         super(constraintClass, messageSource, targetTypes)
         this.mappingContext = mappingContext
     }

grails-datamapping-validation/src/main/groovy/org/grails/datastore/gorm/validation/constraints/factory/DefaultConstraintFactory.groovy

@@ -47,11 +47,7 @@ class DefaultConstraintFactory implements ConstraintFactory {
 
     protected final Constructor constraintConstructor
 
-    DefaultConstraintFactory(Class<? extends Constraint> constraintClass, MessageSource messageSource) {
-        this(constraintClass, messageSource, [Object] as List<Class>)
-    }
-
-    DefaultConstraintFactory(Class<? extends Constraint> constraintClass, MessageSource messageSource, List<Class> targetTypes) {
+    DefaultConstraintFactory(Class<? extends Constraint> constraintClass, MessageSource messageSource, List<Class> targetTypes = [Object]) {
         this.type = constraintClass
         this.name = Introspector.decapitalize(constraintClass.simpleName) - 'Constraint'
         this.messageSource = messageSource

grails-geb/src/testFixtures/groovy/grails/plugin/geb/support/ContainerSupport.groovy

@@ -34,27 +34,7 @@ import grails.plugin.geb.ContainerGebSpec
  * @author Mattias Reichel
  * @since 4.2
  */
-// GROOVY-11907 follow-up / indy=false bytecode bug: @CompileStatic on a trait
-// with static fields generates invalid bytecode for the static setter helpers
-// when the downstream consumer is compiled with grailsIndy=false. The
-// Trait$Helper methods come out with mismatched local slots (e.g. dload_3 on
-// a 2-local frame) and trip a JVM VerifyError ("get long/double overflows
-// locals") at ContainerGebSpec class init, cascading into NoClassDefFoundError
-// on every spec that extends ContainerGebSpec.
-//
-// Fixed for Groovy 5.0.6-SNAPSHOT (commit 74da8078b5 on grails8-groovy5-sb4
-// restored @CompileStatic for Groovy 5). Tracked upstream as GROOVY-11968
-// (apache/groovy PR #2495 by @paulk-asert):
-//   https://issues.apache.org/jira/browse/GROOVY-11968
-//   https://github.com/apache/groovy/pull/2495
-//
-// Standalone reproducer (`TraitStaticFieldsCheck.groovy` in `quick-checks/`):
-//   https://github.com/jamesfredley/groovy5-compiledynamic-trait-bug/tree/main/quick-checks
-//
-// Status to re-verify against latest Groovy 6.0.0-SNAPSHOT before each canary
-// rebuild: if the fix has propagated to the Groovy 6 line, drop @CompileDynamic
-// and switch back to @CompileStatic.
-@CompileDynamic
+@CompileStatic
 @SelfType(ContainerGebSpec)
 trait ContainerSupport implements DownloadSupport {
 

grails-gsp/core/src/main/groovy/org/grails/gsp/compiler/GroovyPageCompiler.groovy

@@ -109,25 +109,11 @@ class GroovyPageCompiler {
             }
             compilerConfig.setTargetDirectory(targetDir)
             compilerConfig.setSourceEncoding(encoding)
-            // GSP compilation parallelism is intentionally configurable via the
-            // grails.gsp.compiler.parallelism system property. The default is
-            // 1 (serial) under Groovy 6 because Groovy 6.0.0-SNAPSHOT contains
-            // a thread-safety bug in org.codehaus.groovy.util.ListHashMap that
-            // surfaces during AnnotationNode.isTargetAllowed -> NodeMetaDataHandler
-            // .getNodeMetaData -> Map.computeIfAbsent on shared annotation
-            // metadata (e.g. @Inject, @CompileStatic) when multiple GSPs are
-            // compiled concurrently. The symptom is "General error during
-            // instruction selection: Index N out of bounds for length N" with
-            // an ArrayIndexOutOfBoundsException in ListHashMap.toMap. Falling
-            // back to a single thread eliminates the race at a small cost in
-            // wall-clock time. Override with -Dgrails.gsp.compiler.parallelism=N
-            // (or 0 to use availableProcessors*2) once Groovy 6 fixes this.
-            int parallelism = computeGspCompilerParallelism()
-            ExecutorService threadPool = Executors.newFixedThreadPool(parallelism)
+            ExecutorService threadPool = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors() * 2)
             CompletionService completionService = new ExecutorCompletionService(threadPool)
             List<Future<Map>> futures = []
             try {
-                Integer collationLevel = parallelism
+                Integer collationLevel = Runtime.getRuntime().availableProcessors() * 2
                 if (srcFiles.size() < collationLevel) {
                     collationLevel = 1
                 }
@@ -188,48 +174,6 @@ class GroovyPageCompiler {
         return compileGSPRegistry
     }
 
-    /**
-     * Resolves the worker-thread count for parallel GSP compilation.
-     *
-     * Honours -Dgrails.gsp.compiler.parallelism=N. A value of 0 (or any
-     * non-positive number) means "use availableProcessors() * 2" (the
-     * historical Grails default). When the property is unset we default
-     * to 1 on Groovy 6 (see the inline comment at the call site for why)
-     * and to availableProcessors() * 2 on Groovy 5 and earlier.
-     */
-    private static int computeGspCompilerParallelism() {
-        int cores = Runtime.getRuntime().availableProcessors()
-        int defaultParallelism = isGroovy6OrLater() ? 1 : cores * 2
-
-        String override = System.getProperty('grails.gsp.compiler.parallelism')
-        if (override == null || override.isEmpty()) {
-            return defaultParallelism
-        }
-        try {
-            int requested = Integer.parseInt(override.trim())
-            if (requested <= 0) {
-                return cores * 2
-            }
-            return requested
-        } catch (NumberFormatException ignore) {
-            return defaultParallelism
-        }
-    }
-
-    private static boolean isGroovy6OrLater() {
-        String version = groovy.lang.GroovySystem.getVersion()
-        if (version == null || version.isEmpty()) {
-            return false
-        }
-        try {
-            int dot = version.indexOf('.')
-            int major = Integer.parseInt(dot >= 0 ? version.substring(0, dot) : version)
-            return major >= 6
-        } catch (NumberFormatException ignore) {
-            return false
-        }
-    }
-
     /**
      * Compiles an individual GSP file
      *

grails-views-core/src/main/groovy/grails/views/AbstractGroovyTemplateCompiler.groovy

@@ -82,25 +82,11 @@ abstract class AbstractGroovyTemplateCompiler {
 
     void compile(List<File> sources) {
 
-        // Mirror the GSP-side guard in GroovyPageCompiler: Groovy 6.0.0-SNAPSHOT
-        // contains a thread-safety bug in org.codehaus.groovy.util.ListHashMap
-        // reachable through AnnotationNode.isTargetAllowed ->
-        // NodeMetaDataHandler.getNodeMetaData -> Map.computeIfAbsent on shared
-        // annotation metadata when multiple template compiles concurrently
-        // touch the same AST. Surfaces in CI as
-        //   General error during instruction selection: Index N out of bounds
-        //   java.lang.ArrayIndexOutOfBoundsException ... at ListHashMap.toMap
-        // during :grails-test-examples-*:compileGsonViews. Default to a single
-        // worker on Groovy 6 to dodge the race; preserve the historical
-        // availableProcessors() * 2 default on Groovy 5 and earlier. Override
-        // with -Dgrails.views.compiler.parallelism=N once Groovy 6 fixes this
-        // (or 0 to use availableProcessors() * 2 explicitly).
-        int parallelism = computeParallelism()
-        ExecutorService threadPool = Executors.newFixedThreadPool(parallelism)
+        ExecutorService threadPool = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors() * 2)
         CompletionService completionService = new ExecutorCompletionService(threadPool)
 
         try {
-            Integer collationLevel = parallelism
+            Integer collationLevel = Runtime.getRuntime().availableProcessors() * 2
             if (sources.size() < collationLevel) {
                 collationLevel = 1
             }
@@ -157,47 +143,6 @@ abstract class AbstractGroovyTemplateCompiler {
         compile(Arrays.asList(sources))
     }
 
-    /**
-     * Resolves the worker-thread count for parallel template compilation.
-     * Honours -Dgrails.views.compiler.parallelism=N. A non-positive override
-     * means "use availableProcessors() * 2" (the historical default). When the
-     * property is unset we default to 1 on Groovy 6 (see the inline comment at
-     * the call site for the ListHashMap thread-safety reasoning) and to
-     * availableProcessors() * 2 on Groovy 5 and earlier.
-     */
-    private static int computeParallelism() {
-        int cores = Runtime.getRuntime().availableProcessors()
-        int defaultParallelism = isGroovy6OrLater() ? 1 : cores * 2
-
-        String override = System.getProperty('grails.views.compiler.parallelism')
-        if (override == null || override.isEmpty()) {
-            return defaultParallelism
-        }
-        try {
-            int requested = Integer.parseInt(override.trim())
-            if (requested <= 0) {
-                return cores * 2
-            }
-            return requested
-        } catch (NumberFormatException ignore) {
-            return defaultParallelism
-        }
-    }
-
-    private static boolean isGroovy6OrLater() {
-        String version = groovy.lang.GroovySystem.getVersion()
-        if (version == null || version.isEmpty()) {
-            return false
-        }
-        try {
-            int dot = version.indexOf('.')
-            int major = Integer.parseInt(dot >= 0 ? version.substring(0, dot) : version)
-            return major >= 6
-        } catch (NumberFormatException ignore) {
-            return false
-        }
-    }
-
     static void run(String[] args, Class<? extends GenericViewConfiguration> configurationClass, Class<? extends AbstractGroovyTemplateCompiler> compilerClass) {
         if (args.length != 7) {
             System.err.println("Invalid arguments: [${args.join(',')}]")